It's one of my all time fave albums. Agree that it's a "have to be in the right mood" one also!
A great memory for me is a car load of us in my brothers pimped BMW back around 1990 went to a place known as Sheep Wash in the North Yorks moors and stopped by a babbling brook with a rustic wooden bridge over it and my bro played it right through on a very good for the time car stereo with all the doors open while we (ahem) smoked a few phat ones and drank a few cans... We were all transported to that special place Astral Weeks can be when you're definitely in the mood for it, and as it finished, quiet, contemplative, and feeling quite at one with nature/the universe... maybe "the healing" Van sometimes refers to in his lyrics(?).